Shroud ring for an axial flow turbine

Abstract

In a device for sealing the gap between the rotor blades and the casing (2) of a turbomachine, configured with a conical profile (28), the rotor blades (6) are provided with circumferential shroud plates (11), which seal by serrations (12, 13, 14, 15) against the casing with the formation of radial gaps (16, 17, 18). The shroud plate (11), which is arranged at the end of the blade, has four throttle locations relative to the casing, the inlet end throttle location bounding a diagonal gap (19) and the outlet end throttle location forming a radial gap (16).

What is claimed as new and desired to be secured by letters patent of the United States is: 
     
       1. A device for sealing the gap between the rotor blades and the casing of a turbomachine, configured with a conical profile, in which the rotor blades are provided with circumferential shroud plates, which seal by means of serrations against the casing with the formation of radial gaps, wherein the shroud plate, which is arranged at the end of the blade, has four throttle locations relative to the casing, the inlet end throttle location forming a diagonal gap in the steady-state operating condition. 
     
     
       2. The device as claimed in claim 1, wherein the outlet end throttle location forms a radial gap. 
     
     
       3. The device as claimed in claim 1, wherein the shroud plates are configured so as to be symmetrical about the axis of rotation. 
     
     
       4. The device as claimed in claim 1, wherein the dividing lines between adjacent shroud plates till extend in the direction of the profile chord. 
     
     
       5. The device as claimed in claim 4, wherein the dividing line fill is provided with four steps, the steps extending in the axial plane of the serrations. 
     
     
       6. The device as claimed in claim 1, wherein the casing is provided with honeycomb arrangements at the four throttle locations. 
     
     
       7. The device claimed in claim 1, wherein the casing is provided with a gap relief chamber at the inlet end of the blade, and the end of the blade the is angled relative to the casing profile at the inlet such that a resulting positive offset at the end of the blade portion together with the associated shroud plate part into the gap relief chamber formed in the casing. 
     
     
       8. The device as claimed in claim 1, wherein the serrations of the shroud plates forming the throttle locations are tapered in the circumferential direction at the shroud plate overhangs. 
     
     
       9. The device as claimed in claim 1, wherein the flow duct wall which adjoins the outlet end honeycomb arrangement is slightly rounded before it makes the transition to the slope of the duct profile.